HTTP, TCP, UDP protocol finishing

HTTP protocol

Hypertext transfer protocol, here you need to understand a concept what is a transfer protocol

Transmission protocol: when the client and server communicate, the format of the transmission data is standardized

As a hypertext transfer protocol, it is currently the most widely used network protocol on the Internet.

Features

• Advanced protocol based on TCP/IP
• Default port number: 80
• Based on the request/response model: one request corresponds to one response
• Stateless: each request is independent of each other and cannot exchange data

Common status codes

1XX: Server receiving is not completed, return 1XX status code

2XX: indicates success
200: the client and server process successfully
3XX: the client needs further operations to complete
304: cache
302: redirect
4XX: client error
404: resource not found
405: method not found
5XX: server error
500: The server code is wrong

The difference between get and post requests

• get request
  • Get data from the server
  • The size of the parameters carried is limited, 4K
  • Not safe
  • The get method can only support ASCII characters, and the Chinese characters transmitted to the server may be garbled.
• post request
  • Send data to the server
  • There is no limit to the size of the parameters
  • Safety
  • Post supports the standard character set and can correctly transmit Chinese characters.

What is the difference between request forwarding and redirection in http?

• Request forwarding

​ 1. Server behavior
​ 2. The address bar has not changed
​ 3. Forwarding is a request
4. Forwarding can only jump to internal resources

• Redirect
  1. Client behavior
  2. Address bar will change

  3. The redirection is a second request

  4. Redirection can jump to any resource

http和tcp

http: short connection, stateless, irrelevant language.

tcp: long connection, stateful, related language.

udp and tcp

• UDP
  1. no connection
  2. The size of each datagram is within 64K
  3. Unreliable agreement
  4. No need to establish a connection, fast
• TCP
  1. Long connection, forming a channel for data transmission
  2. Mass data transfer in the connection
  3. Reliable agreement
  4. Three handshake to complete the connection, low efficiency